Die-casting is a type of casting method in which, by forcing a melted nonferrous metal into a die under pressure, a high-precision casting having a superior casting surface can be mass-produced. The die comprises a cavity (product section) that corresponds with the shape of the product, and a passage (non-product section) through which the melted nonferrous metal flows to the cavity.
Patent Literature 1 (PTL 1) discloses a casting method that uses a die-casting die. In typical die-casting, the inside of the die is first evacuated down to reduced pressure using a vacuum apparatus or the like, and the molten metal (the melted nonferrous metal) is then poured into a plunger sleeve. The molten metal passes through the plunger sleeve and a runner, and fills the cavity. The filled molten metal is cooled and solidified, and the metal is then released from the die as the product.
For example, a compressor housing or the like, which represents one example of a pressure vessel, is produced by die-casting. FIG. 7 illustrates one example of a compressor housing. FIG. 7 illustrates a scroll-type compressor 100 for a car air-conditioning unit. The scroll-type compressor 100 has a housing 102 that constitutes the outer shell. The housing 102 is composed of a front housing 103 and a rear housing 104, which are fastened into a single integrated unit using bolts 105.
A sealing material 106 such as an O-ring is interposed at the bonding interface between the front housing 103 and the rear housing 104, thereby sealing the intake chamber formed inside the housing 102 in an airtight manner relative to the external atmosphere.